Gasoline containing corrosion inhibitor



GASOLINE CONTAINING CORROSION INHIBITOR No Drawing. Application April 1,1952, Serial No. 279,925

7 Claims. (Cl. 44-60 The present invention relates to corrosioninhibitors for gasolines having high octane ratings, and especiallythose gasolines designed for use in aircraft type internal combustionengine. More particularly, it relates to corrosion inhibitors formed asreaction products from alkyl acid phosphates and certain amines, and,which are compatible with other desirable additives. It further relatesto anti-corrosive gasoline and means for producing the same. It alsorelates to the means for manufacturing corrosion inhibitors.

Recently, corrosion inhibitors for gasoline have attained importance asa result of research designed to inhibit corrosion in fuel systems andstorage tanks, particularly where moist gasoline may come in contactwith such metals as iron, copper, brass or the like. This type ofcorrosion is caused usually by the presence of water, and occursgenerally at the water-gasoline interface. Furthermore, variouscomponents used in leaded gasolines are thought to be active promotersof corrosion. g

The appearance of water as a separate phase in aviation gasoline may becaused either by entrained water from the fueling pumps used in fuelingaircraft, since these use water displacement to pump the gasoline; or,by moisture in the air above the gasoline in the fuel tank, since, attemperatures prevalent in high altitude flying, the moisture condensesand precipitates.

Another class of important additives often used in aviation gasoline iscomposedof certain anti-knock agents designed particularly for richmixture operation. Foremost among these additives are aniline and itshomologs, such as for example, ethyl aniline, methyl aniline, amylaniline, diamyl aniline, cumidine, and xylidine. These aromatic aminesare very effective for this particular purpose when used in proportionsof about one to three percent of the gasoline, and function as cumenesubstitutes in aviation gasoline blends.

Although corrosion inhibitors and the above mentioned anti knock agentsfunction excellently when each isz'used in the absence of the other,many of the common corrosion inhibitors are not compatible therewithaConsequent- -ly, when many of the alkyl acid'phosphate-amineneutralization products conventionally used for anti-corrosion purposesare added to a gasoline containing aniline or a homolog of aniline, anundesirable precipitate or-haze forms. The deleterious effects ofprecipitates in liquid fuels are well recognized, and in this instancethey may Amino bicyclo hexyl, also know as amino dicyclo hexyl StatesPatent 2,728,646 Patented Dec. 27, 1955 or carbon substituted cyclohexylcyclohexyl amine, may be produced as either the ortho, para, or metaisomers, each of which is satisfactory for use in the present invention.

While certain variations and deviations from the teachings of thepresent invention are encompassed within its scope and spirit, it isnevertheless recommended that the process of manufacturing the finishedgasolines containing desired additives be carried out in specifiedsteps. For example, the order of addition of materials as well as themethod of mixing the components must follow definite patterns.

The amine and alkyl acid phosphate may be reacted, or neutralized, bymixing the theoretical neutralizing quantities of the two components,heating above room temperature, care being taken not to exceedtemperature at which decomposition takes place, and then thoroughlymixing until reaction is complete. The reaction product is tested todetermine the degree of neutralization, and after neutralization isconfirmed as complete, said reaction product is then blended intogasoline as desired, or may be blended into a small amount of gasolineto be used as a gasoline concentrate. The aniline or homolog thereof maybe added in whatever order desired. However, the aminealkyl acidphosphate neutralization product is insoluble in aniline and itshomologs and as a consequence thereof a one package additive is notpractical.

Another procedure for manufacturing the novel reaction products whichinhibit corrosion comprises dissolving the amine or gasoline concentrateof amine in the gasoline to be treated, and then adding a predeterminedamount of alkyl acid phosphate. Alternately, the alkyl acid phosphatemay be added to the gasoline and then the required amount of amine.added. The blend is then mixed thoroughly for about a half-hour toinsure complete reaction. A similar procedure may be followed for thepreparation of a gasoline concentrate, should this be desired. The blendor concentrate is then tested for degree of neutralization, and whenfound to be satisfactory as evidenced by its non-precipitation ornon-haze formation, the aniline or its homolog, or a gasolineconcentrate thereof, may then be added and the gasoline thoroughly mixedfor ultimate use.

It is an important qualification of the present process that the anilineor homolog thereof never be mixed with a blend containing the alkyl acidphosphate until all of the acidity of the alkyl acid phosphate has beenneutralized by the amine. To test the degree of neutralization, thefollowing procedure has been found to be effective. A drop of thereaction mixture is added to a 1% solution of aniline in aviationgasoline. If precipitation occurs on mixing then a small additionalquantity of the amine is added to the reaction mixture with continuedheating and agitation. This procedure is followed until anon-precipitating reaction product is finally formed from the alkyl acidphosphate and amino bicycle hexyl.

The alkyl acid phosphates which may be used in the neutralization stepof the present process are those having from 8 to 16 carbon atoms peralkyl group. Mainly for commercial reasons, the preferred alkyl acidphosphate is Lorol acid phosphate, which is a mixture of the phosphoricesters of Lorol alcohol. The term Lorol alcohol is used in the trade todenote a mixture of primary normal aliphatic alcohols of 8 to 12 carbonatoms which are obtained by fractionation of the alcohols resulting fromthe reduction of cocoanut and/or palm kernel oils. Lorol acid phosphatemixtures are readily obtainable on the market and for this reason arepreferred to the more purified esters of greater scarcity and higherprice. One Lorol acid phosphate is sold under the trade name Ortholeurn162 and is understood to be mainly a mixture of mono and di acidphosphates of Lorol alcohol. Though for the reasons stated above Lorolacid" phosphates are preferred, other alkyl acid phosphates containingfrom 8 to 16 carbon atoms per alkyl group are satisfactory. For example,a commercial grade of n=octyl acid phosphate was found to produce anexcellent reaction product.

To form the'de'sir'ed neutralization product, the proper proportions ofamino bicyclo hexyl and alkyl acid phosphate may readily be determinedby an electrome'tric titration of a sample of the alkyl acid phosphatewith aqueous KOH solution to a pHof' about 9. From the amount of KOHused the quantity of amine required to neutralize the acid radicals ofthe phosphate may easily becalculated. It is always desirable to' have aslight excess of amine present, and good results have beenobtained withas much as 50% excess of amino bicyclo hexyl.

In order to prevent corrosion effectively, the lower concentration limitof the reaction. product with respect to the finished gasoline should beabout 0.002% by Weight. This was determined by means of'ASTM' D665-47Tcorrosion test modified to a-hath temperature of 80'82 F. The upperconcentration limit is determinedbythat amount of neutralization productwhich would cause engine deterioration clue to the excessive quantity ofphosphates then present. The upper limit is about 0.05% by weight.

Certainembodiments of the present invention are more fully illustratedby thefollowing examples:

Example 1 Into a suitable vessel equipped with means for heating,agitating, and'cooling the charge, there are introduced 154' parts byweight of ortho amino bicyclo hexyl, followed gradually by 150 parts ofa mixture of mono. and di.

Lorol acid phosphates (Ortholeum 162). The mixture is agitatedvigorously and cooled as required to keep the temperature below 200 F.The reaction is vigorous'and exothermic, consequently the rate ofaddition of the phosphate is controlled to avoid exceeding the abovetemperature limit. The resulting mixture is stirred for about 1 hour at140 F. The reaction product is a viscous, oily liquid, yellow in color.v The reaction product is then tested for neutrality by means of theaforementioned neutralization test, and, if found to be acid, additionalamino bicyclo hexyl'is added. Finally, five pounds of the finishedadditive are added to 17,000 gallons of aviation gasoline in a blenderand agitated for about 15 minutes. Then 1020 pounds of mixed xylidinesare added and the mixture resulting therefrom. is agitated for about ahalf-hour. The final gasoline is completely homogeneous, free from haze,corrosion resistant, and has a rich mixture anti-knock ratingcommensurate with the amount of xylidines used.

Example II A 10% by weight solution in gasoline of the finished additivefrom Example I is prepared by dissolving 100 pounds of the reactionproduct in 900 pounds of gasoline in a mixer. The gasoline-additiveconcentrate is thoroughly mixed for about one hour, and 50 pounds ofthis concentrate then blended into 17,000 gallons of aviation gasoline.The resulting mixture is agitated for about minutes. Finall, 1020 poundsof mixed xylidines are added and mixing continued for an additional 30minutes. This finished product is comparable to that obtained in Examplei.

Example III To 17,000 gallons of aviation gasoline in a blender areadded 2.94 lbs. of ortho amino bicyclo hexyl. The resulting mixture isthoroughly agitated for about 10 minutes, and then 2.68 pounds of amixture of mono and di Lorol. acid phosphate (Ortholeurn 162) are addedwith continued mixing for about one-half hour. After the neutralizationtestsindicate theproduction of a satisfac- 4 tory reaction product, 1020pounds of mono methyl aniline are added and" a'g'i't'atit'an continuedfor another halfhour. As in the former examples, tests indicate theproduction of excellent quality finished gasoline.

Example IV The same procedure is used as in Example I except that 77parts by'weight of 'meta' amino bicyclo'hexyl are used in lieu of 154'parts by weight of ortho amino bicyclo hexyl; and, parts by weight ofOrtholeum 162 is used in lieu of parts by weight.

Example V factory reaction product, 340 pounds of mono methyl anilineare added and agitation continued for another half-hour. As in theformer examples, tests indicate theproduction of excellent qualityfinished gasoline.

Although aviation gasolines are used inthe above examples forpurposes ofillustration, and such gasolines may comprise the following:

Alkylate 70-88% Aromatics 516%. Isop'entane 5-14%. Tetra ethyl lead. 4cc. per gallon.

nevertheless, the. invention in its broadest scope comprehends thetreatment of any motor fuel. Similarly, it will be appreciated'that' thereaction product of the present invention may be blended in properproportions in any desired: gasolinewith the-advantage that thepurchaseror user may add any suitable amount of aniline or homologsthereof, for the purpose of obtaining. rich mixture anti-knockproperties, without difiiculties arising from precipitation or hazeformation which is generally encountered when less satisfactorycorrosion inhibitors are used.

It will now be apparent that I' have devised a novel and useful processand composition of matter which embodies-the features of advantageenumerated as desirable in: the statement of the invention and the abovedescription and while in the present instance there are described thepreferred embodiments th'ereofiwhi'ch have been found in practice togive satisfactory and reliable results, it is to be' understood that thesame is susceptible of modification in=v various: particulars withoutdeparting from the spirit or scope of the invention or sacrificing anyof its advantages.

I claim:

1. A completely homogeneous, corrosion-resistantaviation' fuel having ahigh rich mixture anti-knock rating, comprising gasoline containing.sufficient aromatic amine from the group consisting of aniline. andhomologs of aniline to substantially increase the rich mixtureantiknoclc' properties of the gasoline and between 0.002% and 0.05% byweight of the' finished gasoline of the addition product resulting fromcontacting an alkyl acid phosphate having from 8 to 16 carbon atoms peralkyl group with between 1.00% and 150% of the quantity theoreticallyrequired to neutralize said phosphate of amino bicyclo hexyl.

2. An anti-corrosive gasoline as in claim 1 wherein the amino bicyclohexyl is ortho amino bicyclo hexyl.

3'. An anti-corrosive gasoline as in claim 1 wherein the amino bicyclo.hexyl'is meta aminobicyclo hexyl.

4'. An anti-corrosive gasoline as in claim 1 wherein the alkyl acidphosphate is a phosphoric acid ester derived from a mixture of primarynormal aliphaticalcohols of 8 to" 12 carbon atoms obtainable by thefractionation of alcohols resulting from the reduction of cocoanut oil.

5. An anti-corrosive gasoline as in claim 1 which contains in additionsufiicient tetraethyl lead to increase the anti-knock properties.

6. The method of simultaneously improving the anticorrosive and the richmixture anti-knock properties of a gasoline, which comprises forming insaid gasoline a corrosion inhibiting amount of the addition product ofan alkyl acid phosphate having 8 to 16 carbon atoms per alkyl group andamino bicyclo hexyl and in which all the acid hydrogen of said phosphateis neutralized by said amino bicyclo hexyl, then adding suflicientaromatic amine from the group consisting of aniline and homologs ofaniline to substantially increase the rich mixture anti-knockproperties.

7. The method of inhibiting the formation of an insoluble precipitatewhen an amine-phosphate corrosion inhibitor is added to a gasolinecontaining an aniline octane booster, which comprises adding to agasoline an alkyl acid phosphate having 8 to 16 carbon atoms per alkylgroup, adding between 100% and about 150% of the quantity theoreticallyrequired to neutralize all the acid hydrogen of said phosphate of aminobicyclo hexyl thereby forming in said gasoline an addition product ofsaid amine with said phosphate, then adding sufficient aromatic aminefrom the group consisting of aniline and homologs of aniline tosubstantially increase the rich mixture anti-knock properties of thegasoline, the amounts of the amino bicyclo hexyl and the alkyl acidphosphate being sufficient to produce an addition product of between0.002% and 0.05% by weight of the finished gasoline.

References Cited in the file of this patent UNITED STATES PATENTS2,297,114 Thompson Sept. 29, 1942 2,413,262 Stirton Dec. 24, 19462,550,982 Eberz May 1, 1951 2,656,375 Vaughn Oct. 20, 1953 FOREIGNPATENTS 222,547 Germany Nov. 2, 1942

1. A COMPLETELY HOMOGENEOUS, CORROSION-RESISTANT AVIATION FUEL HAVING AHIGH RICH MIXTURE ANTI-KNOCK RATING, COMPRISING GASOLINE CONTAININGSUFFICIENT AROMATIC AMINE FROM THE GROUP CONSISTING OF ANILINE ANDHOMOLOGS OF ANILINE TO SUBSTANTIALLY INCREASE THE RICH MIXTURE ANTIKNOCKPROPERTIES OF THE GASOLINE AND BETWEEN 0.002% AND 0.05% BY WEIGHT OF THEFINISHED GASOLINE OF THE ADDITION PRODUCT RESULTING FROM CONTACTIN ANALKYL ACID PHOSPHATE HAVING FROM 8 TO 16 CARBON ATOMS PER ALKYL GROUPWITH BETWEEN 100% AND 150% OF THE QUANTITY THEORETICALLY REQUIRED TONEUTRALIZE SAID PHOSPHATE OF AMINO BICYCLO HEXYL.